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            <h1 style="display: none">Object|Array之实例创建</h1>
            
            <div class="markdown-body" id="post-body">
              <h3 id="1-对象实例的创建"><a href="#1-对象实例的创建" class="headerlink" title="1.对象实例的创建"></a>1.对象实例的创建</h3><h4 id="1-new操作符"><a href="#1-new操作符" class="headerlink" title="1.new操作符"></a>1.new操作符</h4><pre><code class="hljs js"><span class="hljs-keyword">let</span> person = <span class="hljs-keyword">new</span> <span class="hljs-built_in">Object</span>();
<span class="hljs-comment">//可以通过访问属性来动态创建属性</span>
person.name = <span class="hljs-string">&quot;Sarry&quot;</span>;
person.age = <span class="hljs-number">20</span>;</code></pre>

<h4 id="2-对象字面量-使用较多"><a href="#2-对象字面量-使用较多" class="headerlink" title="2.对象字面量(使用较多)"></a>2.对象字面量(使用较多)</h4><p>对象定义的简写形式，目的在于简化创建大量的属性的对象的过程。但是需要注意的是，对象字面量的创建并不会调用Object的构造函数</p>
<pre><code class="hljs js"><span class="hljs-keyword">let</span> individual = &#123;
    name: <span class="hljs-string">&quot;Sarry&quot;</span>,
    age: <span class="hljs-number">20</span>
&#125;</code></pre>

<p><code>注意：在最后一个属性添加逗号，会在IE7及更早的版本和Opera中导致错误</code></p>
<ul>
<li>这里的花括号是出现在<code>上下文表达式</code>中，故左边的花括号意味着对象字面量的开始；而出现在<code>语法上下文</code>，是代表语法块的开始</li>
<li>如果形参需要传递大量的可选参数，ES5的做法是使用对象，不过ES6中新增了默认参数值的设定</li>
</ul>
<h4 id="3-属性访问-方括号所特有的"><a href="#3-属性访问-方括号所特有的" class="headerlink" title="3.属性访问(方括号所特有的)"></a>3.属性访问(方括号所特有的)</h4><ul>
<li>通过变量访问属性</li>
<li>导致语法错误的字符，比如中间有空格是我字符串</li>
<li>属性名为关键字或保留字</li>
</ul>
<div class="note note-info">
            <p>一般情况下，都是通过点语法访问属性，但是上面这些特殊情况使用点语法会报错，这时就只能使用方括号语法访问。</p>
          </div>

<h3 id="2-数组的创建"><a href="#2-数组的创建" class="headerlink" title="2.数组的创建"></a>2.数组的创建</h3><h4 id="1-new操作符-1"><a href="#1-new操作符-1" class="headerlink" title="1.new操作符"></a>1.new操作符</h4><h5 id="1-1-仅有一个数字时"><a href="#1-1-仅有一个数字时" class="headerlink" title="1.1 仅有一个数字时"></a>1.1 仅有一个数字时</h5><pre><code class="hljs js"><span class="hljs-keyword">let</span> array = <span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">10</span>); <span class="hljs-comment">// 注意：这时创建一个length为10的空数组</span></code></pre>

<h5 id="1-2其他"><a href="#1-2其他" class="headerlink" title="1.2其他"></a>1.2其他</h5><pre><code class="hljs js"><span class="hljs-keyword">let</span> music = <span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-string">&quot;jazz&quot;</span>); <span class="hljs-comment">// [&quot;jazz&quot;]</span>
<span class="hljs-keyword">let</span> mix = <span class="hljs-keyword">new</span> <span class="hljs-built_in">Array</span>(<span class="hljs-number">3</span>, <span class="hljs-string">&quot;juice&quot;</span>, <span class="hljs-literal">true</span>); <span class="hljs-comment">// [3, &quot;juice&quot;, true]</span></code></pre>

<h4 id="2-对象字面量-使用较多-1"><a href="#2-对象字面量-使用较多-1" class="headerlink" title="2.对象字面量(使用较多)"></a>2.对象字面量(使用较多)</h4><p>同样，数组字面量的创建并不会调用Array的构造函数</p>
<pre><code class="hljs js"><span class="hljs-keyword">let</span> array = [<span class="hljs-number">3</span>]; <span class="hljs-comment">// 这就是创建了一个数组项，要注意构造器的差异</span>
<span class="hljs-keyword">let</span> mix = [<span class="hljs-number">3</span>, <span class="hljs-string">&quot;juice&quot;</span>, <span class="hljs-literal">true</span>];</code></pre>

<p>哈哈，是不是字面量的创建更简洁，据说效率比构造器要高一点</p>

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